Preliminary assesment of Araucaria araucana resilience to extreme drought events

SERGIO PIRAINO; ARCO MOLINA, JULIETA; HADAD, MARTÍN A.; FIDEL A. ROIG

Lund

Congreso; TRACE 2021 TREE RINGS IN ARCHAEOLOGY, CLIMATOLOGY AND ECOLOGY (TRACE 2021); 2021

TRACE

Extreme climatic events represent disturbance factors shaping forest dynamics, inducing decline in growth and die-off episodes, furthermore modifying tree resilience. Araucaria araucana (Molina) K. Koch, an iconic northern patagonian conifer, is considered an endangered species according to IUCN classification. We applied dendroecological and statistical methods to reconstruct resilience, in terms of resistance and recovery, of 10 forest stands to three successive extreme dry spells occurred during the 20th century, with particular attention to site conditions (xeric vs. mesic environments). Resistance and recovery showed differences along the considered dry spells, with a decrease in resistance for the more recent drought, whereas recovery values on the opposite showed an increasing trend. Xeric woodlands were less resistant than forest located in mesic areas, while recovery did not show any difference among the selected environments. At the tree-level, we found an inverse relation among resistance and recovery indices in xeric stands, suggesting possible different strategies when facing extreme droughts. Resistance (recovery) in both environments was positively (negatively) associated with tree growth, represented by basal area increment values. Tree age positively influenced growth resistance but only in mesic environment. These findings suggest that the A. Araucana is less resilient to extreme droughts in xeric than in mesic environments. The expected increase in frequency and intensity of extreme drought for northern Patagonia suggests that the emerged results should be considered in conservation plans of this natural resource.